FRI238 A Rare Combination Of Thyroiditis And Secondary Adrenal Insufficiency Likely Secondary To Hypophysitis In A Patient Treated With Immune Checkpoint Inhibitors

Disclosure: S. Patel: None. O.A. Aluko: None. E. Thwe: None. T. Gallagher: None. M. Deshmukh: None. Introduction: Immune checkpoint inhibitors have shown significant improvement in treatment of various cancers. Thyroiditis and hypophysitis are well-known reported adverse effects of immune checkpoint inhibitors. However, the co-existence of thyroiditis and hypophysitis in patients treated with immune checkpoint inhibitors is rare. We hereby report a case of a patient with thyroiditis and secondary adrenal insufficiency secondary likely to hypophysitis who was treated with atezolizumab for hepatocellular carcinoma. Case Report: A 65 year old male with past medical history of type 2 diabetes mellitus, hepatocellular carcinoma status post transcatheter arterial chemoembolization on atezolizumab and bevacizumab, thyrotoxicosis, liver cirrhosis secondary to prior alcohol use presented to the ED for evaluation of intermittent dizziness. Vitals signs showed Temperature 97.7°F, BP 137/64 mmHg, HR 82 beats/min, RR 18 breaths/min, SpO2 98%. During the hospital course, work up revealed AM cortisol level of 0.7 μg/dL (N 4.2-22.4 μg/dL), ACTH 33 pg/dL (N 7.2-63.3 pg/dL), TSH <0.007 uIU/mL (N 0.45-4.5 uIU/mL), free t4 3.57 ng/dL (N 0.76-1.46 ng/dL), free t3 6.84 pg/mL (N 2.3-4.2 pg/mL), TSI <0.1 IU/L (0-0.55 IU/L), TRAb <1.1 IU/L (N 0-1.75 IU/L), anti-microsomal antibody <8 IU/mL (N 0-24 IU/mL), anti-thyroglobulin <1 IU/mL (0-0.9 IU/mL). Nuclear medicine uptake scan showed abnormally low 24 hr uptake indicative of thyroiditis in the setting of clinical and biochemical hyperthyroidism. MRI pituitary with and without contrast revealed normal appearing pituitary gland. Patient was subsequently started on prednisolone 30mg in AM and 10mg in PM to treat for thyroiditis as well as secondary adrenal insufficiency likely secondary to hypophysitis. Patient had improvement in symptoms of dizziness on prednisolone. Conclusion: This case highlights the co-existence of endocrinopathies associated with immune checkpoint inhibitor use. Though thyroiditis and hypophysitis are very well associated with immune checkpoint inhibitor use, co-existence of thyroiditis and hypophysitis is rare. This case illustrates the importance of having high index of suspicion for co-existence of endocrinopathies in patients treated with immune checkpoint inhibitors. Presentation: Friday, June 16, 2023